Sudden unexpected infant deaths account for close to half of all deaths in the postneonatal period. Sudden infant death syndrome (SIDS) is the single leading cause of postneonatal mortality and is responsible for half of the unexpected deaths. The remaining deaths (hereafter called sudden unexpected deaths in infancy or "SUDI") are caused by suffocation/asphyxiation, other injuries, infections, homicide, unspecified, and other causes. Despite reductions in the rate of SIDS for all racial/ethnic groups since the Back to Sleep campaign began, Blacks still experience twice the incidence of SIDS and postneonatal mortality compared with Whites. Further, rates of SIDS and postneonatal mortality have stabilized. In order to reverse these disturbing trends, it is critical to better understand and address the factors associated with both SIDS and other SUDI. This study proposes to analyze previously collected data from the Chicago Infant Mortality Study (CIMS) to measure the association between prenatal and neonatal, social, and environmental factors and the risk for SUDI. The aims are to identify risk factors: 1) for SUDI, focusing largely on a high-risk, African American population; 2) that are common to both SIDS and SUDI; and 3) that differ between SIDS and SUDI. CIMS is the most comprehensive case-control study of SIDS and SUDI ever conducted. It used standardized diagnostic procedures including autopsy, death scene investigation, and review of the clinical history to make the distinction between SIDS and other causes of SUDI. CIMS includes 260 infants who died from SIDS and 209 who died from SUDI (November 1993-April 1996). The majority of infants (76.8%) were African American; 13.4% were White, Hispanic and 9.8% were White, non-Hispanic. Living control infants were matched to the case infants on race/ethnicity, birth weight and age. Analyses will compare the SUDI and SIDS case infants with their respective controls; odds ratios (OR), 95% confidence intervals (Cl), and P-values will be calculated. Multivariate conditional logistic regression will be run using the stepwise method for selection of variables. The ratio of the SIDS and SUDI ORs and associated CIs and P-values will be computed to detect any potential differences between them. Identifying risk factors for SUDI will aid in the development of educational interventions that target these potentially preventable causes of infant death. Learning the risk factors that are common to both SIDS and SUDI will enable interventions to target multiple disorders simultaneously with consistent messages. Finally, by examining differences in risk factors between SIDS and other SUDI, we expect to provide further epidemiological evidence that supports the unique role of adverse prenatal and postnatal environmental exposures in the causal pathway of SIDS. The NICHD's strategic plan for SIDS focuses on reducing disparities through the investigation of factors operating within and across populations. The results of this study will help guide preventive strategies, with the long-term goal of further reducing the incidence of SIDS and SUDI, eliminating racial/ethnic disparities in these causes of infant mortality, and achieving national targets established by Healthy People 2010. [unreadable] [unreadable] [unreadable] [unreadable]